There have been many variations on this idea of "letting kids learn on their own". The basic issue is the one you highlight, which is that it works if the student is very self motivated. Most students aren't. Or rather, they're highly motivated to do other things.
I think if you can get into the chemistry just a bit, then the math behind the chemistry, it can be a vehicle. I mean it's the same with programming. Why write code (boring, yuck) when you could play video games? Then the kids see code makes video games. Suddenly you have all these programs with kids making Minecraft mods or whatever. But finding each child's "bomb" would be hard for a teacher to do, especially with a common curriculum
In the early days they were using off the shelf curriculum software and layering their own steering AI over it.